Hi,
check that the airflow in your pc case is constant.
If something blocks it, dirty fans, no proper cable managment, cat in front of pc
clean it. I have an I7 930, a big Antec case, a big cpu cooler Nehalem, all 4 fans (Nexus 120 mm)
run at 800 rpm. Very good airflow, cpu temp doesn't go over 55 degrees C at 100 percent usage.
Just a good constant airflow does the trick, it can be a low and quiet one.
Also keep in mind that windows 7 does run a small defrag in the background, a very well hidden background task,
just google for it how to disable this. Your free space on the HDD ain't enough for this.
Another tip to defrag faster, is to attach preferably internally, an empty drive. Move your files to this drive,
this makes you external one empty.. no frag at all, and move your files back to the external.
The move operation is a lot faster than windows defragmentation, and the end result is even beter.
Also keep in mind that e-sata for the moment only supports SATA2, not SATA3 yet. I guess the new e-sata cables
for SATA3 will be out on the market in 1, maybe 2 months. You can Always build your external one, inside your case.
I hope this helps a bit.